放牧对荒漠草原优势植物叶片养分含量和化学计量特征的影响

Effects of Grazing on Leaf Nutrient Content and Stoichiometric Characteristics of Dominant Plants in Desert Steppe

[目的]阐明荒漠草原优势植物叶片养分含量对不同放牧强度的响应。[方法]在内蒙古短花针茅荒漠草原的放牧样地上设置4个不同放牧强度的处理:对照(CK)、轻度放牧(LG)、中度放牧(MG)和重度放牧(HG),载畜率分别为0、0.91、1.82、2.71只羊/hm^(2)。于2020年对荒漠草原优势植物短花针茅(Stipa breviflora)、无芒隐子草(Cleistogenes songorica)、银灰旋花(Convolvulus ammannii)和冷蒿(Artemisia frigida)在不同放牧强度下叶片中的C、N、P浓度进行测定,并对其化学计量特征进行计算。[结果]与对照区(CK)相比,重度放牧显著(P<0.05)降低了短花针茅和银灰旋花叶片的C浓度;放牧对短花针茅、无芒隐子草、银灰旋花和冷蒿叶片N含量无显著(P>0.05)影响;中度放牧显著(P<0.05)增加了短花针茅和银灰旋花叶片的P浓度,并显著(P<0.05)降低了冷蒿的P浓度;重度放牧显著(P<0.05)降低了银灰旋花的C∶N,短花针茅、银灰旋花和冷蒿的C∶P,以及短花针茅的N∶P。[结论]放牧改变植物对养分的利用状况,不同植物对相同生境有不同的适应策略。放牧降低荒漠草原优势植物固C能力。长期中度放牧有利于荒漠草原优势植物对N、P的吸收。

[Objective]To better understand how dominant plants′leaf nutrient content and stoichiometric characteristics respond to varying grazing intensities in the desert steppe.[Method]On the grazing sample plots of Stipa breviflora desert steppe in Inner Mongolia,four treatments with varied grazing intensities were set up:control(CK),light grazing(LG),moderate grazing(MG),and heavy grazing(HG),with stocking rates of 0,0.91,1.82,and 2.71 sheep/hm^(2) respectively.In the year of 2020,under varying grazing intensities,the concentrations of C,N,and P in leaves of domoinant plants Stipa breviflora,Cleistogenes songorica,Convolvulus ammannii and Artemisia frigida were measured,and their stoichiometric properties were calculated.[Result]Compare with CK group,heavy grazing significantly(P<0.05)decreased the leaf C concentration of Stipa breviflora and Convolvulus ammannii.Grazing had no significant(P>0.05)effect on the leaf N content of all four dominant plants tested.Moderate grazing significantly(P<0.05)increased the P concentration in the leaves of Stipa breviflora and Convolvulus ammannii,while significantly(P<0.05)decreased the P concentration of Artemisia frigida.Heave grazing significantly(P<0.05)decreased the C∶N of Convolvulus ammannii,the C∶P of Stipa breviflora,Convolvulus ammannii and Artemisia frigida as well as the N∶P of Stipa breviflora.[Conclusion]Grazing alters plants′nutrient utilization.Different plants have different adaptation strategies to the same habitat.Grazing reduces the C fixation capacity of dominant plants in desert steppe.Long-term moderate grazing promotes the absorption of N and P by dominating plants in desert steppe.